Concrete casting shuttering

ABSTRACT

Successively raisable shuttering for the casting of upwardly or downwardly tapering concrete structures, comprising two mutually opposed and horizontally displaceable form portions for forming the tapering surfaces of the structure, which are interconnected by a mechanism coupled to a raising system for the shuttering so that the form portions are displaced inwardly or outwardly by a predetermined amount during each raising step of the raising system.

United States Patent [72] Inventor Guido Lambertini H2, Via Saragozza,Bologna, Italy 211 Appl. No. 765,492

[22 Filed Oct. 7, I968 [45] Patented July 20, 1971 [32] Priority Oct.10, 1967, July 31, 1968 [33] Italy [Ill] 814223 and 7210 A/68 [54}CONCRETE CASTING SHUTTERING l8,20,2l,22,48,49;25/I31 A, 131 H, 131 EM,I31 EY, 131 SA, I31 SB, 131 SC, 131 SD;6l/46,

[56] References Cited UNITED STATES PATENTS 235L759 9/1958 Berntsen A.25/l31 (SB) 3,425,659 2/1969 Eriksson 25/13] (S) X FOREIGN PATENTS864,377 4/1961 Great Britain 25/131 (SB) Primary Examiner-.l. SpencerOverholser Assistant ExaminerLucius R. Frye Attorney-Stanley I. RosenABSTRACT: Successively raisable shuttering for the casting of upwardlyor downwardly tapering concrete structures, comprising two mutuallyopposed and horizontally displaceable form portions for forming thetapering surfaces of the structure, which are interconnected by amechanism coupled to a raising system for the shuttering so that theform portions are displaced inwardly or outwardly by a predetermined 52amount during each raising step of the raising system.

/02 20 I /o2 /5 l5 [II 2 202 205 3 8 203 202 2 /0/ 3 m lo/ PATENTEDJULZOISY; 3,593,392

SHEET 1 0F 5 6/1/00 L AMBER T/lV/ BY J M M ATTORNEY INVENTOR PATENTEDJUL20 l9?! SHEET 3 OF 5 INVENTOR 60/00 LAMBERT/1W ATTORNEY PATENTEUJUL20 19m SHEET U [1F 5 INVENTOR GU/DO LAMBERT/All M AfioRNEY CONCRETECASTING SHUTTERING BACKGROUND OF THE INVENTION fastened to the top ofthe shuttering and climb. upwardly on verticalsteel rods set intoandprojecting fror n'the concrete structure.

It is a principal object of the invention to provide a successivelyraisable form of shutteringof the kind referred to above, for theconstruction of upwardly narrowing or widening concrete structures. 1

SUMMARY According to the invention'successively raisable'shuttering foruse in thecasting of a tapering concrete structure is providedcharacterized by two mutually opposed form portions which arehorizontally displaceablerelative to eachother, at least one displacingmechanism interconnecting the form portions, and a raising systemztowhich the displacing mechanism is coupled, the displacing. mechanismbeing arranged for simultaneous operation with the raising system todisplace both form portions inwardly oroutwardly by a predeterminedamount during each raising step of the raising system.

In the preferred embodiment of the successively raisable shuttering, theshuttering is also narrowed or widened at the same time in thehorizontal directionduring each raisingstep owing .to the reciprocaloutwardly or inwardly directed displacement of the two opposed formportions, the ratio between the raisingstep and the correspondinghorizontal displacement step of the form portions being chosen in such amanner as to produce the required constant narrowing or widening of theconcrete structure.

The two form portions which are reciprocally displaceable in thehorizontal direction may bedirectly interconnected by means of thedisplacing mechanism.

' According to another feature of the invention however, the shutteringcomprises an interposed raisable connecting part on which the two formportions are displaceably guided, and synchronously driven displacingmechanisms connecting the form portions to the connecting part, whichdisplacing mechanisms actin opposite directions for reciprocalhorizontal displacement of the form portions.

This construction is advantageous for shuttering of greater width inparticular, and ensures more precise displacement of the displaceableform portions. Moreover, a given maximum distance of travel of eachseparate displacing mechanism secures'an approximatelydoubled-reciprocal maximum displacement of the two form portions,thereby extending the range of application of the formwork and at leastreducing the onerous setting-up and resetting procedures.

In the case of shuttering comprising a hydraulic or pneumatic raisingsystem, the raising mechanism and the displacing mechanism arefluid-operated, a common pressurized fluid supply is provided, and ashared control device connects the fluid feed-supply to the raisingmechanism and the displacing mechanism. In this construction, thesimultaneous actuation of the raising system and of the displacingmechanisms and consequently also the required simultaneity of theraising movement and of the horizontal displacement of the formportions, is assured by simple means.

Further according to the invention, each displacing mechanism consistsof a mechanical feed mechanism which is connected to a fluid-operatedactuating device. In this construction, the ratio between the raisingstep and the corresponding horizontal displacement step of the formportions may-be varied by modification of the transmission ratio in'themechanical-feed mechanism and may be adapted to the narrowing orwidening of the concrete structureas required in each case, whereas thecorrespondinghydraulic or pneumaticactuating'device still has the'samepressure acting upon it, and fluctuations of this pressure do notexercise any influence on the displacement ofthe shuttering.

The shuttering according'to the invention may be employed for productionof concrete structures which are formed by a single vertical concreteunit comprising two opposed, upwardly converging or diverging slopingareas, and two vertical lateralsurfaces. For-such cases, the inventionmakes provision for a closed shuttering assembly, in which the two formportions which are displaceable in horizontal direction are madeU-shaped, and embrace the concrete unit in the region of the obliquesurfaces of the unit, and have correspondingly sloping end walls andoverlap each other with their lateral branches in the area of thevertical lateral surfaces of the concrete unit, inlongitudinallydisplaceable manner. If a connecting portion is interposedin this construction between the two displaceable U-shaped-formportions, this connecting portion is formed, to complement theshuttering at both vertical sides of the concrete unit, by auxiliaryshuttering plates which overlap the lateral branches of the displaceableU-shaped form portions.

The shuttering according to the invention may moreover be employed inadvantageous manner for the production of concrete structures whichconsist of two individualupwardly converging or diverging piers, columnsor the like of constant crosssection. In this case, according to theinvention, the two horizontally displaceableform portions are individualforms closed on themselves annularly, and each encircling one of thepiers and correspondingly inclined, whilethe connecting portionpreferably interposed between these individual form portions-consistsofa horizontal bearer arranged at one side of the pair of piers, on whichthe two individual'forms are guided in longitudinally displaceablemanner by means of saddles or carriages. This construction allows thesimultaneous production of two convergent or divergent concrete piers,concrete columns or the like, by means of the raisable formwork elementswhich were not applicable to this purpose until now.

BRIEF DESCRIPTION OFTHE DRAWINGS FIG. 1 shows in elevation raisableshuttering according to the invention for the production of a concreteunit which constantly diminishes in width upwardly,

FIG. 2 shows the shuttering of FIG. 1 in diagrammatic plan view,

FIG. 3 shows a part of the shuttering of FIG. I, in elevation and tolarger scale,

FIGS. 4 and 5 are cross sections along the lines IV-IV and V-V of FIG.3, to larger scale, p FIG. 6 shows in elevation shuttering according tothe invention for the simultaneous production of two upwardly convergingconcrete piers,

FIG. 7 shows the shuttering of FIG. 6, in diagrammatic plan view,

FIG. 8 shows a part of the shuttering of FIG. 6, in elevation and tolargerscale,

FIG. 9 shows the shuttering part of FIG. 8, in plan view, and

FIG. 10 is a cross section along the line X-X of FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENT The raisable steel shutteringillustrated in FIGS. I to 5 is intended for the production of a concreteunit I, for example a bridge pier or the like, which has a rectangularbase area and a width which constantly diminishes upwards, that is, theunit I is delimited on two'opposite sides by upwardly converging slopingsurfaces 101 and on the other two sides by vertical lateral surfaces'201. The shuttering employed for producing this concrete unit 1,possessesa corresponding rectangular cross section and is of closedform, consisting of two opposed U-shaped form portions 2 which cnflankthe oblique surfaces 101 of the concrete unit 1 and have correspondinglyinclined end walls 102, and two plane form plates 3 constituting theshuttering at either side of the concrete unit 1 in the area of thevertical lateral surfaces 201 of the same. The U-shaped form portions 2overlap the associated lateral form plates 3 with the lateral branches202 of the form plates 3, and the form portions 2 are displaceablyguided in these lateral branches 202 in the horizontal direction. Tothis end, each lateral form plate 3 has an outwardly open section whichis approximately U-shaped in vertical section, at least in the area ofits two terminal portions 203. The branches 202 of the U shaped formportions 2, which are also of U-shaped section, are displaceably guidedin the profiled terminal portions 203 of the lateral form plates 3.

The lateral branches 202 of each U-shaped form portion 2 has a verticalcrosspiece 7 (FIG. 3) at its free end, with which the form portions aredisplaceably guided on two horizontal guide rods 4 situated one abovethe other in the corresponding terminal portions 203 of the lateral formplates 3.

The guide rods 4 are fastened at one end on a vertical crosspiece 5 ofthe form plate 3 and at the other end to an upright 6 by means ofinwardly projecting brackets (FIG. 5), this upright 6 being situated onthe corresponding outer extremity of the form plate 3 at the outer sideof the branch 202 of the U-shaped form portion 2.

The branches 202 of each U-shaped form portion 2 are each connected tothe lateral form plates 3 by means ofa displacing mechanism indicatedgenerally at 8. The displacing mechanisms 8 interposed between aU-shaped form portion 2 and the lateral form plates 3 then have areversed sense of operation relative to the displacing mechanisms 8interposed between the other U-shaped form portion 2 and the lateralform plates. All displacing mechanisms 8 have the same structure and areso constructed and synchronously driven, that in each case, theysimultaneously displace the U-shaped form portions 2 inwardly, i.e.towards each other relative to the lateral form plates 3.

In particular, each displacing mechanism 8 consists of two horizontalscrew spindles 9 arranged one above the other, for rotation withoutdisplacement in the axial direction, and are mounted in the crosspiece 5of the lateral form plate 3 and in the inwardly projecting brackets 106of the upright 6 on the outer extremity of the form plate 3. Each screwspindle 9 is threaded through an associated spindle nut 10 which isfastened in the crosspiece 7 of the corresponding lateral branch 202 ofthe U-shaped form portion 2. The two screw spindles 9 are positivelycoupled to each other by means of a chain drive 11, 12, so that theyturn in the same direction, The screw spindles 9 are driven by means ofa stepping mechanism 13, known per se, which is coupled through thechain drive 11, 12 to a spindle, and is actuated by means ofa rockinglever 14. The rocking lever 14 is driven by means of a hydraulicallyoperating cylinder 15 mounted on the form plate 3 and by retractionsprings 16.

The shuttering composed of the lateral form plates 3 and thedisplaceable U-shaped form portions 2 has a relatively small heightcompared to the overall height of the concrete unit 1 to be produced,and is raised successively in steps after the setting or solidificationof the lower concrete layers. The raising system employed for thispurpose consists of hydraulic climbing hoists 17, known per se, whichare secured at the top to the lateral form plates 3 as well as to theU-shaped form portions 2, and climb upwardly on vertical steel rods 18set into the concrete unit 1 and projecting upwardly therefrom.

The climbing hoists 17 of the raising mechanism and the drivingcylinders 15 of all the displacing mechanisms 8 interposed between theform plates 3 and the displaceable U- shaped form portions 2 areconnected to the same hydraulic system 19 and may be connectedsimultaneously to the pressurized fluid infeed 120 by means of a sharedcontrol device 20. Consequently, during actuation of the control device20,

the climbing hoists 17 as well as the cylinders 15 of the displacingmcchanisms 8 receive a driving thrust, so that the whole shuttering 2,3is raised by a step, and both U-shaped form portions 2 are displacedinwardly simultaneously, i.c. towards each other in horizontal directionrelative to the lateral form plates 3. The ratio between the raisingstep and the simultaneous horizontal displacement step of the U- shapedform portions 2 corresponds to the slope ofthe oblique surfaces 101 ofthe concrete unit 1, and may be set or varied by modification of thetransmission ratio in the mechanical part of the displacing mechanisms8, specifically by the incorporation of screw spindles 9 and spindlenuts 10 of different pitch.

The raisable steel shuttering illustrated in FIGS. 6 to 10 is for thesimultaneous production of two upwardly converging piers 21, each ofwhich has a rectangular constant cross section. The shuttering consistsof two separate steel forms 22 which are annularly closed, each forforming one of the piers 21, and possessing a corresponding crosssection. These separate forms 22 which lean towards each other with theangle of convergence of the piers 21 have a relatively small heightcompared to the overall height of the piers 21 and are simultaneouslyraised successively by means of a shared hydraulic raising system. Thisconsists of known hydraulically operated climbing hoists 17 which arefastened to the tops of both separate forms 22 and climb upwardly onvertical steel rods 18 set into the concrete piers 21 and projectingfrom the same. All the climbing hoists 17 are connected to the samehydraulic system 19 and are simultaneously connected through a sharedcontrol device 20 to the pressurized fluid infeed 120.

The two separate forms 22 are arranged displaceably on horizontalconnecting bearers 23 situated at either side of the piers 21 andraisable together with the separate forms 22. in the embodimentillustrated, each separate form 22 is connected at either side with acarriage 24, which runs in the longitudinal direction on thecorresponding horizontal bearer 23 and is guided on the same, The twocarriages 24 are fastened to the coordinated separate forms 22 by meansof vertical iron sections 25 and angled coupling shackles or the like26. Each carriage 24 consists of two head portions 124 spaced apart fromeach other, which enflank the corresponding horizontal coupling bearer23 and bear on the upper side as well as on the underside of the bearerby means of rollers 27. The two head portions 124 of each carriage 24are interconnected at both sides of the corresponding horizontal bearer23 by means of longitudinally directed sidewalls 224 constructed inlatticelike manner.

Each carriage 24 is connected to the corresponding bearer 23 by means ofa displacing device indicated generally at 28 for the longitudinaldisplacement of the carriage on the bearer. This displacing device 28consists of two screw spindles 29 which extend in the longitudinaldirection of the horizontal bearer 23 and are situated above and belowthe bearer. One end of each screw spindle 29 is rotatable withoutdisplacement in axial direction in a pivot bearing 129 which isconnected to the one end part 124 of the carriage 24 so as to swivelabout a horizontal transverse axis. The other freestanding end of thescrew spindle 29 is threaded through an associated spindle nut 30 whichis swivelably arranged about a horizontal transverse axis on thecorresponding bearer 23 by means of a bearing block l30. The two screwspindles 29 are positively coupled to each other by means of a chaindrive 31, 32, so that they turn in the same direction. The drive to thescrew spindles 29 is through a stepping mechanism 33 known per so, whichis coupled to the chain drive 31, 32,'or to the spindle 29, and isdriven by means of a rocking lever 34. The rocking lever 34 is actuatedby a hydraulic operating cylinder 35 arranged on the carriage 24, incombination with a retraction spring which is not illustrated.

The two displacing mechanisms 28 cooperating with one of the separateforms 22 and situated at either side of the same are operated in opposedmanner to the two displacing mechanisms 28 cooperating with the otherseparate form 22 and also situated at either side of the latter. That isthe displac mg mechanisms 28 of the two separate forms are soconstructed and arranged that under simultaneous actuation, theydisplace the coordinated pairs of carriages 24-24, and consequently thetwo separate forms 22, synchronously towards each other on thehorizontal connecting bearers 23.

All the displacing mechanisms 28 for the horizontal displacement of thetwo separate forms 22 are actuated at the same time as the climbinghoists 17 for the raising of the framework. To this end, the actuatingcylinders 35 of the displacing mechanisms are connected to the samehydraulic system 19 as the climbing hoists l7 and are connected at thesame time as these to the pressurized fluid infeed 120 by means of thesame control device 20, and are therefore acted upon by the pressurizedfluid. During each actuation of the control device 20, and at the sametime as the climbing hoists 17, the hydraulic cylinders 35 of thedisplacing mechanisms 28 thus receive a driving thrust and operate thecoordinated screw spindles 29 through the switching or stepping devices33. Consequently, the two separate forms 22 are simultaneously displacedhorizontally towards each other during each raising step, by one step onthe connecting bearers 23. The ratio between the raising step and thereciprocal horizontal displacement step of the two separate forms 22corresponds to the angle of convergence of the two concrete piers 21, sothat the two piers can be built up at the same time. in this case too,the angle of inclination of the two convergent concrete piers 21 may beset and varied by modification of the transmission ratio in themechanical part of the displacing mechanisms 28, specifically byexchange of the screw spindles 29 and of the corresponding spindle nuts30.

To avoid the application of excessively long screw spindles 29 and theconsequent inaccuracies resulting from bending and twisting of thespindles, the length of the screw spindles 29 corresponds to a fractiononly of the total distance of horizontal displacement which has to becovered by each raisable separate form 22 along the total height of theconcrete pier 21 to be produced. Consequently, if at a definiteintermediate height of the convergent concrete piers 21, the screwspindles 29 have been screwed almost completely through their associatedspindle nuts 30, the nuts are freed from the connecting bearers 23 andrefastened on the bearers 23 in another position displaced furtherinwardly i.e. towards the vertical median symmetry plane of the pair ofpiers 21. To this end, each connecting bearer 23 is formed with severalgroups of holes 36 spaced apart from each other in the longitudinaldirection, in which the bearing block [30 of each spindle nut 30 may befastened by means of screwbolts or the like at different distances fromthe median vertical symmetry plane of the pair of piers 21 on theconnecting bearer 23, and may thus be advanced progressively towards thesaid symmetry plane.

The invention is not limited to the examples illustrated, and severalsolutions differing in the structural sense in particular, are possiblewithin the scope of the general principle of the invention. Inparticular, the displacing mechanisms 8 and 28 may be so constructed,e.g. by reversing the pitch of the screw spindles 9 and 29, that theycause a simultaneous outwardly directed horizontal displacement of theform portions 2 and 22 during each raising step of the formwork. Thisarrangement allows the construction of concrete units 1 having upwardlydiverging oblique surfaces 101, or the construction of piers 21 whichdiverge upwardly. The displacing mechanisms 8, 28 themselves may be ofdifferent structure from that of the screw spindle embodiment,especially in their mechanical part.

lclaim:

l. Successively raisable shuttering for use in the casting ofa taperingconcrete structure, comprising two mutually opposed form portionshorizontally displaceable relative to each other, at least onedisplacing mechanism interconnecting the form portions, a raising systemto which the displacing mechanism is coupled, said displacing mechanismbeing arranged for simultaneous operation with the raising system todisplace both form portions inwardly or outwardly by a predeterminedamount during each raising step of said raising system, an m terposedraisable connecting part on which said two form portions aredisplaceably guided, synchronously driven displacing mechanismsconnecting said form portions to said connecting part and operable inopposite directions for reciprocal horizontal displacement of said formportions, fluid means for operating said raising mechanism and saiddisplacing mechanism, a pressurized fluid supply, a control deviceinterconnecting said fluid operating means to said pressurized fluidsupply for simultaneous operation of said raising mechanism and saiddisplacing mechanism, said displacing mechanism comprising a mechanicalfeed mechanism connected to said fluid operating means and includingseveral parallel screw spindles positively coupled to each other, afluid-operated cylinder to which said screw spindles are coupled formovement in the same sense, spindle nuts on said screw spindles, and astepping gear connecting said cylinder to said spindle nuts.

2. Shuttering according to claim 1, characterized in that a chain drivecouples said screw spindles to each other.

3. Shuttering according to claim 1, characterized in that the length ofeach of said screw spindles is a fraction only of the total horizontaldisplacement of the associated form portion considered over the entireheight of said concrete structure, and each displacing mechanismincludes means for stepped displacement of the point of connection ofsaid spindle nuts on said connecting part.

4. Shuttering according to claim 1, characterized in the the length ofsaid screw spindles of each displacing mechanism is a fraction only ofthe total horizontal displacement of the associated form portionconsidered over the entire height of said concrete structure, and eachdisplacing mechanism includes.

means for stepped displacement of the point of connection of saidspindle nuts on said connecting part.

5. Successively raisable shuttering for use in the casting of a taperingconcrete structure, comprising two mutually opposed form portionshorizontally displaceable relative to each other, at least onedisplacing mechanism interconnecting the form portions, a raising systemto which the displacing mechanism is coupled, said displacing mechanismbeing arranged for simultaneous operation with the raising system todisplace both form portions inwardly or outwardly by a predetenninedamount during each raising step of said raising system, an interposedraisable connecting part on which said two form portions aredisplaceably guided, synchronously driven displacing mechanismsconnecting said form portions to said connecting part and operable inopposite directions for. reciprocal horizontal displacement of said formportions, said concrete structure consisting of a single uprightconcrete unit having two opposed extending oblique surfaces and twovertical lateral surfaces, said form portions being U-shaped forembracing said oblique surfaces and having inclined end walls for'forming the oblique surfaces of the concrete unit, and cooperatinglateral branches for forming areas of the vertical lateral surfaces ofsaid concrete unit.

6 Shuttering according to claim 5, characterized in that said connectingpart between said form portions comprise auxiliary shuttering plates ateither side of the concrete unit in the area of the vertical lateralsurfaces of the unit, said plates overlapping the later branches of thedisplaceable U-shaped form portions.

7. Shuttering according to claim 1, in which said concrete structureconsists of two separate upwardly converging or diverging piers ofconstant cross section, wherein the two horizontally displaceable formportions are formed as separate units each annularly closed, and eachencircling one of the piers and being appropriately inclined to matchthe inclination of that pier.

8. Shuttering according to claim 7, wherein the connecting partinterposed between the two separate displaceable form potions consistsof at least one horizontal bearer situated at one side of tlie piers,and carriages connected to the form portions and running on the bearerto effect longitudinal displacement of the form portions.

1. Successively raisable shuttering for use in the casting of a taperingconcrete structure, comprising two mutually opposed form portionshorizontally displaceable relative to each other, at least onedisplacing mechanism interconnecting the form portions, a raising systemto which the displacing mechanism is coupled, said displacing mechanismbeing arranged for simultaneous operation with the raising system todisplace both form portions inwardly or outwardly by a predeterminedamount during each raising step of said raising system, an interposedraisable connecting part on which said two form portions aredisplaceably guided, synchronously driven displacing mechanismsconnecting said form portions to said connecting part and operable inopposite directions for reciprocal horizontal displacement of said formportions, fluid means for operating said raising mechanism and saiddisplacing mechanism, a pressurized fluid supply, a control deviceinterconnecting said fluid operating means to said pressurized fluidsupply for simultaneous operation of said raising mechanism and saiddisplacing mechanism, said displacing mechanism comprising a mechanicalfeed mechanism connected to said fluid operating means and includingseveral parallel screw spindles positively coupled to each other, afluid-operated cylinder to which said screw spindles are coupled formovement in the same sense, spindle nuts on said screw spindles, and astepping gear connecting said cylinder to said spindle nuts. 2.Shuttering according to claim 1, characterized in that a chain drivecouples said screw spindles to each other.
 3. Shuttering according toclaim 1, characterized in that the length of each of said screw spindlesis a fraction only of the total horizontal displacement of theassociated form portion considered over the entire height of saidconcrete structure, and each displacing mechanism includes means forstepped displacement of the point of connection of said spindle nuts onsaid connecting part.
 4. Shuttering according to claim 1, characterizedin the the length of said screw spindles of each displacing mechanism isa fraction only of the total horizontal displacement of the associatedform portion considered over the entire height of said concretestructure, and each displacing mechanism includes means for steppeddisplacement of the point of connection of said spindle nuts on saidconnecting part.
 5. Successively raisable shuttering for use in thecasting of a tapering concrete structure, comprising two mutuallyopposed form portions horizontally displaceable relative to each other,at least one displacing mechanism interConnecting the form portions, araising system to which the displacing mechanism is coupled, saiddisplacing mechanism being arranged for simultaneous operation with theraising system to displace both form portions inwardly or outwardly by apredetermined amount during each raising step of said raising system, aninterposed raisable connecting part on which said two form portions aredisplaceably guided, synchronously driven displacing mechanismsconnecting said form portions to said connecting part and operable inopposite directions for reciprocal horizontal displacement of said formportions, said concrete structure consisting of a single uprightconcrete unit having two opposed extending oblique surfaces and twovertical lateral surfaces, said form portions being U-shaped forembracing said oblique surfaces and having inclined end walls forforming the oblique surfaces of the concrete unit, and cooperatinglateral branches for forming areas of the vertical lateral surfaces ofsaid concrete unit.
 6. Shuttering according to claim 5, characterized inthat said connecting part between said form portions comprise auxiliaryshuttering plates at either side of the concrete unit in the area of thevertical lateral surfaces of the unit, said plates overlapping the laterbranches of the displaceable U-shaped form portions.
 7. Shutteringaccording to claim 1, in which said concrete structure consists of twoseparate upwardly converging or diverging piers of constant crosssection, wherein the two horizontally displaceable form portions areformed as separate units each annularly closed, and each encircling oneof the piers and being appropriately inclined to match the inclinationof that pier.
 8. Shuttering according to claim 7, wherein the connectingpart interposed between the two separate displaceable form potionsconsists of at least one horizontal bearer situated at one side of thepiers, and carriages connected to the form portions and running on thebearer to effect longitudinal displacement of the form portions.